title: A murine monoclonal antibody (928) recognizing a new epitope formed with a combination of HLA-DPA1*0201 and DPB1*0301 gene products.
abstract: A murine monoclonal antibody (mAb), 928, that recognizes a cell surface antigen (928 Ag) on a human Epstein-Barr virus-transformed fetal liver-derived lymphoid progenitor cell line (FL4.4) was generated. The 928 mAb reacted with only FL4.4; it did not react with any other 57 cell lines tested. Two color flowcytometry analysis of peripheral blood mononuclear cells (PBMC) revealed that the 928 mAb reacted with B cell and monocyte fractions from only two individuals out of 63 unrelated donors. Biochemical analyses showed that the 928 Ag composes of two molecules (33 and 34 Kd) and forms a SDS-resistant, noncovalently linked dimer conformation, the feature being similar to that of peptide-bound MHC class II molecules. Treatment of FL4.4 cells with the 928 mAb significantly facilitated homotypic cell aggregation. In addition, treatment of PBMC of the 928 Ag+ donor with recombinant IL-4 augmented the expression of the 928 Ag on CD64+ monocytes. Typing of HLA-DRB1, DPA1 and DPB1 alleles of the 928 Ag expressing and nonexpressing cells revealed that the 928 Ag is expressed only on PBMC of HLA-DPA1*0201 and DPB1*0301 positive donors. Finally, anti-DP antibody precleared 928 Ag from the cell lysate. These results demonstrate that the 928 mAb recognizes a polymorphic determinant of HLA-DPA1*0201-DPB1*0301 gene products. The possibility that amino acids in the groove of the peptide-binding site of HLA-DP molecules are critical for the 928 epitope is discussed.
authors.affiliation: Department of Immunology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kishi
authors.forename: A
authors.initials: A
authors.lastname: Okumura
authors.forename: J J
authors.initials: JJ
authors.lastname: Tong
authors.forename: E
authors.initials: E
authors.lastname: Sugiyama
authors.forename: H
authors.initials: H
authors.lastname: Matsuno
authors.forename: J
authors.initials: J
authors.lastname: Minowada
authors.forename: T
authors.initials: T
authors.lastname: Kanai
authors.forename: Y
authors.initials: Y
authors.lastname: Nishimura
authors.forename: A
authors.initials: A
authors.lastname: Muraguchi
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D000954:Antigens, Surface / Q000276:immunology; D002449:Cell Aggregation; D000939:Epitopes / Q000032:analysis* / Q000737:chemistry; D015870:Gene Expression; D005802:Genes, MHC Class II; D006682:HLA-DP Antigens / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D015847:Interleukin-4 / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D000939:Epitopes; D006682:HLA-DP Antigens; D015847:Interleukin-4